Universal answer arrangement for a PABX

Abstract

A universal answer arrangement for a PABX in which incoming trunk calls are automatically connected, when all operator positions are busy or unattended and equipped for universal answer service, to a pre-designated line circuit or, at night, to one or more selected operator position circuits. In response to the connection to an associated operator loop circuit, a programmable automatic dialing circuit transmits a programmable predetermined number to a local register which effects a switch-through from the incoming trunk to the designated line circuit. The operator loop circuit monitors the connection and releases from the call when the called line goes off hook. Advantageously, the night answer arrangement includes a PABX group hunting circuit which permits the incoming call to be connected to a second line circuit if the first line circuit is busy or to a tie line trunk to another PABX having a night attendant if all line circuits in the hunting group are busy or disabled.

What is claimed is: 
     
       1. An answer arrangement for use in a private automatic branch exchange having a plurality of trunks each with a first port for connection to a transmission path from one subscriber and a second port for connection to a transmission path to another subscriber, a switching network through which the trunks may be connected to an operator console via a position circuit in the absence of a position busy indication at the position circuit, common control means responsive to service requests from the trunks for marking a trunk for connection through the switching network and further responsive to the service requests for generating request signals, easn of the plurality of trunks having a trunk circuit means which is actuated for connecting the first and second ports to the switching network and which is deactuated for disconnecting the first and second ports from the switching network and interconnecting the two ports within the trunk, the trunk circuit means being initially actuated when its respective trunk is first marked by the connon control means, and an operator circuit means including first and second transmission pairs for connection, respectively, to the first and second ports of a connected trunk, means responsive to a request signal from the common control for connecting the loop circuit through the switching network to the marked trunk, the answer arrangement comprising: first circuit means for overriding a position busy indication at a position circuit and for permitting a trunk to be connected to the position circuit via the switching network,   second circuit means for inhibiting the transmission of an answer supervision signal from the position circuit to the marked trunk,   third circuit means for utilizing the existing operator circuitry for connecting the marked trunk to a designated destination, and   programmable circuit means arranged to selectively modify the designated destination.   
     
     
       2. An answer arrangement according to claim 1 wherein the programmable circuit means is arranged selectively to connect the marked trunk to any one of a group consisting of a line circuit, a pilot number of a hunting group, a tie line trunk, and a trunk arranged to provide an audible indication of an incoming call. 
     
     
       3. An answer arrangement for use in a private automatic branch exchange having a plurality of trunks each with a first port for connection to a transmission path from one subscriber and a second port for connection to a transmission path to another subscriber, first connecting circuit means through which the trunks may be connected to an operator console via a position circuit in the absence of a position busy indication at the position circuit, second connecting circuit means for marking and connecting a trunk through the first connecting circuit means, each of the plurality of trunks having a trunk circuit means which is actuated for connecting the first and second ports to the first connecting circuit means and which is deactuated for disconnecting the first and second ports from the first connecting circuit means and interconnecting the two ports within the trunk, the trunk circuit means being initially actuated when its respective trunk is first marked by the second connecting circuit means, and an operator circuit means including first and second transmission pairs for connection, respectively, to the first and second ports of a connected trunk, means responsive to a signal from the second connecting circuit means for connecting the loop circuit via the first connecting circuit means to the marked trunk, the answer arrangement comprising: first circuit means for overriding a position busy indication at a position circuit and for permitting a trunk to be connected to the position circuit via the first connecting circuit means,   second circuit means for inhibiting the transmission of an answer supervision signal from the position circuit to the marked trunk,   third circuit means for utilizing the existing operator circuitry for connecting the marked trunk to be designated destination, and   programmable circuit means arranged to selectively modify the designated destination.   
     
     
       4. An answer arrangement according to claim 1 wherein the designated destination comprises an answer trunk arranged to provide an audible indication of the connection of an incoming call to the marked trunk and to the answer trunk. 
     
     
       5. An answer arrangement according to claim 4 wherein the answer trunk is arranged to effect a connection between the incoming trunk and one of a plurality of line circuits in response to signals transmitted from the line circuit. 
     
     
       6. An answer arrangement according to claim 1 further comprising signalling means responsive to the destination designated by the programming means to transmit signals representative of the destination to a connected local register and timing means, responsive to a failure of the signals transmitted to the register to effect a connection to the designated destination after a predetermined time, to generate a release signal to the operator circuit means for releasing the register from the operator circuit means. 
     
     
       7. An answer arrangement according to claim 6 further comprising retry circuit means responsive to the release signal generated by the timing means to attempt another connection to the designated destination. 
     
     
       8. An answer arrangement according to claim 7 further comprising counting means responsive to the failure of a predetermined number of attempts to connect an incoming call to the designated destination for transmitting an operator release signal to the operator circuits for releasing the operator circuits from the marked trunk.